Simulation and analysis of hot water system with comprehensive utilization of solar energy and wastewater heat

With global interest in energy saving and emission reduction, the combination of waste water energy recycling and solar energy has attracted great attention. In this work, a solar-assisted waste water source heat pump hot water system was built in TRNSYS. The sensitivity analysis of different factors on the annual heating performance coefficient of the system was conducted and the optimal parameters were selected to improve the basic scheme. The results revealed that the COP sys and COP HP were highly related to the pump flowrate and the storage capacity of heat exchange tank, but the azimuth and inclination angle of solar collector have slight influence on them. Moreover, the increase of heating capacity of solar collector will lead to the decrease of COP HP , while resulting in the decrease of the heat pump power consumption. The suitable pump flowrate is 4.6 m 3 /h and the appropriate volume of the heat exchange tank is 1 m 3 . The best azimuth angle and inclination angle of the solar collector are 4° south by east and 42°, respectively. The improved system has more stable hot water temperature in winter with significant decrease of the energy consumption. • A hot water system with comprehensive utilization of different energy was built. • The optimized system provides more consistent performance than the original system. • Parametric study was conducted to explore the influences of key parameters on the system performance. • The simulation results were evaluated with specific annual productivity indicators.